To grow large crystals of delta-aminolevulinic acid dehydratase in order to initiate studies on its tertiary structure. To determine at least part of the primary sequence of delta- aminolevulinic acid dehydratase. To determine the nature of the amino group of the enzyme that forms a Schiff base with delta-aminolevulinic acid. To determine the number of metallic ions and their identity in the enzyme. To determine the minimum number of subunits needed for activity. To determine the function of the two proteins necessary for the conversion of porphobilinogen to the functional isomer of porphyrins. To explore further the components of the cell-free extract capable of synthesizing the corrin ring of vitamin B12.